Lockheed L-133: Truly Supersonic?

[KJ_Lesnick]

I remember watching a documentary on the L-133 and they said that from what they knew at the time it would appear to be capable of supersonic flight.  Regardless, what I'm wondering is would it have been able to in actuality?

On one hand

• It had the same basic wing as the P-80 Shooting Star which was not capable of supersonic flight
  
• It didn't appear to have any area-ruling and it might have had excessive cross-sectional area in the mid-section
  

..
However

• It had a canard which would not have suffered a loss in performance from a loss of the wing's downwash at transonic speeds
  
• It had more powerful engines and afterburners
  
• It had an unusual exhaust configuration which used exhaust entraining which could have pulled out some turbulent layer
  

//
What do you guys think?

[Joe C-P]

Would the engine planned for it have had enough power? Was there any real idea of the engine's capabilities?

[KJ_Lesnick]

Would the engine planned for it have had enough power? Was there any real idea of the engine's capabilities?

At least as of 1942 the engine had a takeoff power of 6,700 pounds of thrust (I don't know if that's afterburning or not) at sea-level, weighed 1,235 pounds and was 24 inches in diameter.  I assume at this stage the engine still used an axial flow compressor feeding a reciprocating compressor.

[PR19_Kit]

Would the engine planned for it have had enough power? Was there any real idea of the engine's capabilities?

At least as of 1942 the engine had a takeoff power of 6,700 pounds of thrust (I don't know if that's afterburning or not) at sea-level, weighed 1,235 pounds and was 24 inches in diameter.  I assume at this stage the engine still used an axial flow compressor feeding a reciprocating compressor.

I don't think so.....

By 1942 the L-1000 engine only existed as a design study, the first example didn't even run until 1946! By 1953 only three L-1000s had been built and the project was cancelled. See here :-

http://en.wikipedia.org/wiki/Lockheed_J37

There is one L-1000 still in existence (I've seen it with my own eyes even) at one of the various aviation Museums in California.

[KJ_Lesnick]

Everybody

I'm mostly concerned with the airframe -- could it have gone supersonic based on the airframe?


PR19_Kit

I don't think so.....

I was talking about the listed capability...

From 1938 to 1942 they had largely worked around the premise of an axial flow compressor feeding a reciprocating compressor, by 1942 there were desires to change the design though it's possible by late 1942 the design might still have had the reciprocating compressor (that's where the 1235 pound/24-inch diameter, and 6700 lbs thrust figure was listed).  Afterburning was incorporated from the outset far as I know.

At some point in 1942 to 1943 he revised the design by removing the reciprocating compressor and replacing it with three centrifugal flow impellers with inter-cooling between each stage and a hydraulic clutch to vary the RPM of the engine to fine tune it to altitude.  At this point the engine went up to around 1,700 or so pounds.

By mid-1943 the engine was taken to it's final stage whereby two axial flow spools were incorporated, each incorporating 16-stages, reduced inter-cooling was used between them and a four-stage turbine (2 per spool) was incorporated -- the first four blades of the LP compressor were hooked to a hydraulic clutch producing an effect of having 2.5 spools.  The turbine blades were allegedly to be hollowed with either air or liquid cooling.  The afterburner was to be regeneratively cooled.  Weight was approximately 1,600 pounds.

As far as I know the complexity of the design had to do with producing desirable fuel efficiency figures which probably was to make the design even remotely acceptable by the USAAF.  

Interestingly looking at the range figures of the aircraft I'm wondering if anybody factored in ram-compression, air-temperature differences at altitude, and the fact that the exhaust velocity would be closer to the plane's cruise speed and would yield greater efficiency (also the plane would cruise and dash at similar speeds).  

I don't remember when people started looking at the propeller thrust velocity and the net-thrust issues, and I'm also not sure when people began to realize that if you travel twice as fast but have half the efficiency the range is equally achieved (I'm pretty sure by the 1950's and 1960's this was understood as the B-58, A3J/A-5, and B-70 all worked around this principle, and I suppose to an extent the F-102/F-106 and F-105).

By 1942 the L-1000 engine only existed as a design study, the first example didn't even run until 1946! By 1953 only three L-1000s had been built and the project was cancelled. See here :-

http://en.wikipedia.org/wiki/Lockheed_J37

Oh, I know the design was ridiculously overcomplicated!  While I'm surprised the idea of intercoolers didn't appear in other turbojet designs (they were used in piston engines), it might very well have had to do with the fact that lower pressure ratios were used and the manner of which fuel was tossed into the engine was different.

There is one L-1000 still in existence (I've seen it with my own eyes even) at one of the various aviation Museums in California.

Yeah

[wuzak]

I doubt that the L-133 would truly have been supersonic.

For one thing it used the same basic wing as the P-38, which had a low critical mach number. Lower than the P-47, much lower than the P-51, not to mention the Spitfire.

I also don't think Lockheed engineers had enough of a handle on transonic aerodnamics (nor did anyone else) to make it work, they certainly didn't, in the late 1930s, have a good understanding of compressibility (otherwise the P-38 wing would have been different, I'm sure).

[PR19_Kit]

PR19_Kit

I don't think so.....

I was talking about the listed capability...

You mean what they SAID it would do before they got around to building it?

There's the rub, there's more 'guestimates' in the aviation industry that never get to be proved one way or the other than in almost any other industry. And many mabufacturers are well versed in making such 'guestimates' so that they get the contract and then find out that they guessed wrong and have to ask for more money to do the job that they should have got right in the first place.

[eatthis]

PR19_Kit

I don't think so.....

I was talking about the listed capability...

You mean what they SAID it would do before they got around to building it?

There's the rub, there's more 'guestimates' in the aviation industry that never get to be proved one way or the other than in almost any other industry. And many mabufacturers are well versed in making such 'guestimates' so that they get the contract and then find out that they guessed wrong and have to ask for more money to do the job that they should have got right in the first place.

and heres my thinking im just a cynical git 

[PR19_Kit]

I was born cynical............

[rickshaw]

Cynicism is a useful survival trait.  It battles with the suicidal trait of curiosity all the time.   

[eatthis]

Cynicism is a useful survival trait.  It battles with the suicidal trait of curiosity all the time.   

i have both in abundance 

[KJ_Lesnick]

Wuzak

I doubt that the L-133 would truly have been supersonic.

For one thing it used the same basic wing as the P-38

I'm not sure if that's true -- that's come up before but from what I recall there wasn't a direct connection. 

The wing was similar to the P-80 however: While that wasn't capable of supersonic flight, the L-133 had a canard which would provide superior pitch control (you can't lose the downwash when your pitch control isn't beholden to it) though I'm unsure this would yield an unstable design; it had a blended fuselage which at lower-speed would make for low drag; at high-speed it may have reduced drag, but it might have driven it up (area ruling and such).


PR19_Kit

You mean what they SAID it would do before they got around to building it?

Good point

And many mabufacturers are well versed in making such 'guestimates' so that they get the contract and then find out that they guessed wrong and have to ask for more money to do the job that they should have got right in the first place.

Or knew they were wrong and figured if they got the contract they could do whatever they want.

[martinbayer]

I'm mostly concerned with the airframe -- could it have gone supersonic based on the airframe?

I know it sounds glib, and I don't want to come across as snide, but *anything* can go supersonic with enough engine power, so you can't look at the airframe in isolation from the engine. It's like the adage that "given enough engine power, even a brick can fly." To answer your question, you would have to pick a point in time *when* you would like to evaluate supersonic capability - whether its at the time of airframe conception or *any* time thereafter.

Martin

[Rheged]

 

I was born cynical............

"Blessed is the cynic,  for they shall rarely be surprised!"    to quote a vicar I know. 

I'm inclined to  concur with Martin.  Anything  can go supersonic with enough thrust...........but whether it's a fully  controllable aircraft with a doughty pilot at the helm,   or an uncontrollable hurtling object with a gibbering passenger..........?    That's another consideration entirely.

[KJ_Lesnick]

I know it sounds glib, and I don't want to come across as snide, but *anything* can go supersonic with enough engine power

But who cares if it's uncontrollable during the process?

"Blessed is the cynic,  for they shall rarely be surprised!"    to quote a vicar I know.

LOL 

I'm inclined to  concur with Martin.  Anything  can go supersonic with enough thrust...........but whether it's a fully  controllable aircraft with a doughty pilot at the helm,   or an uncontrollable hurtling object with a gibbering passenger..........?

That's what I mean...